The whole group is facing opposition from political leaders here in Mexico, from the president of the United States and from disgruntled locals.

It could all turn very nasty - it did in Europe.

Doctors say the migrants are exhausted but in reasonable shape.

The problem is that half of them are children and they are very susceptible to breathing illnesses.

On the road they were in fresh air, now they are sleeping in the middle of a camp of adults crammed together on the floor.

Image:Migrants are camping on a baseball field

All refugee camps are miserable and this is no different but it is still manageable, for now.

Despite the efforts of the local authorities and a handful of NGOs to keep the camp clean, an outbreak of diarrhoea and vomiting, I suspect, is a racing certainty.

This will happen when more caravans arrive and they are on the way.

Image:All refugee camps are miserable and this is no different

At least 2,000 more people are already in Mexico and will reach here in the next few days.

It is rumoured that caravans in other countries are being formed up.

Brazil and Venezuela have been mentioned and certainly they are ripe for a mass exodus.

Image:This is the Tijuana beach border with San Diego

If this really does happen then Mexico will be overwhelmed.

How to deal with this is the conundrum.

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Video:Trump declares migrant caravan a national emergency

The US has a functioning asylum system but it is slow - it can only process 100 people a day in Tijuana at best.

It hasn't even remotely turned its attention to the caravans yet.

The fact that President Trump decided to make the caravans a political issue in his efforts to shore up Republican votes in the midterm elections and sent troops to the border to "protect" the country, hasn't helped matters.

Image:Anti-immigrant protests have taken place

Generally speaking, though, this is not a failure by the US - or Mexico for that matter.

The responsibility lies with the governments of countries like El Salvador and Nicaragua for their economic mismanagement and, of course, with the gangs that ruin communities and wreak terrible violence on the most vulnerable.

But the migrants are here now and they will be for a very long time so there needs to be some organised international response.

Image:Tijuana is the current preferred destination for the migrant caravans

President Trump can cast them all as criminals, which they aren't, and the mayor of Tijuana can threaten to kick them all out, which he can't; whatever, something has to be done to at least ensure that people don't start dying from neglect or turn to crime to get money for food.

As a doctor in the camp said to me: "You can't deal with this problem with barbed wire. It has to be dealt with compassion."